The present invention relates to an electric tool configured to use a brushless motor as a driving source.
In recent years, a brushless motor has been adopted in an electric tool configured to rotate a tip tool such as a drill and a driver by a motor, thereby performing a predetermined operation. The brushless motor has, in general, Y connected (star connected) or Δ-connected three-phase windings. The three-phase windings are energized by an inverter. The inverter has switching elements connected to a plus-side and a minus-side of each phase winding (stator coil), i.e., a total of six switching elements, and is configured to sequentially energize the predetermined stator coils. By a magnetic field generated by the stator coils, a rotor having a magnet is rotated. The respective switching elements configuring the inverter are arranged on a switching substrate in the vicinity of the brushless motor.
[Patent Document 1]
Japanese Patent Application Publication No. 2013-831A
When the brushless motor is a three-phase motor and the stator has six poles, for example, two stator coils are provided for each phase. In the brushless motor of the electric tool of the related art, since the stator coils of each phase are connected in series, a resistance (copper loss) of the stator coils with respect to a power supply voltage is large, which is unfavorable for a high output. When a line diameter of the stator coil is increased, it is possible to reduce the resistance. However, a width of a winding slot is limited, so that there is a limitation on the increase in the line diameter.